The US has for the first time publicly said that China was the top suspect in the massive hacking of a US government agency that saw millions of personnel records of Americans compromised.

James Clapper, the director of National Intelligence said that "you have to kind of salute the Chinese for what they did," given the difficulty of the intrusion, the Wall Street Journal quoted him as saying at a Washington intelligence conference.

Reuters said that Clapper's office has confirmed that China has been identified as a leading suspect although investigations are still ongoing.

The Wall Street Journal quoted Clapper as saying that both the government and US companies would remain targets of hackers until policymakers addressed the "lack of deterrents."

This is the first time that President Barack Obama's administration has openly accused Beijing of the hacking of the Office of Personnel Management, according to Reuters. US officials have previously blamed the attacks on Chinese hackers but never publicly.

White House spokesman Josh Earnest on 25 June had declined to comment on any potential suspects.

He however cautioned against guessing at what response the US may take against those responsible for the cyber attacks. "If there is a response, it's probably not one we are likely to telegraph in advance," he said.

The absence of a US threat to respond to hacking attacks meant that Washington had to put its focus on defence instead, the newspaper said, quoting Clapper.

Clapper's comments a day after the conclusion of three days of high-level talks between the US and China in Washington.

US Secretary of State John Kerry had announced at the conclusion of the meeting that both countries had agreed to develop a conduct of conduct.